A catch-all mailbox receives emails sent to non-existent email addresses under the very same domain name. For instance, an email message sent to the miswritten firstname.lastname@example.org will go to email@example.com if the catch-all feature has been enabled for the latter. In this way, you can receive messages from partners or customers who may have sent a message to your email address with a typo or to an old one, which they may still have, but you have already deleted. Just one mailbox per domain can be a catch-all one and email forwarding cannot be activated for such a mailbox. The latter is due to the fact that at a certain moment you may start receiving spam messages in the catch-all mailbox and the forwarding restriction implies that the spam will not be sent to a 3rd-party mailbox.